Positive displacement ventilation system

ABSTRACT

A method includes inflating one or more inflatable bags from a first evacuated condition within an attic space to an inflated condition. The inflatable bags are configured such that when they are in an evacuated condition, they take up a relatively small space in the attic space to be ventilated. In the inflated condition, however, the bags have a cumulative volume much larger than the cumulative volume of the bags when in the evacuated condition, and make up a desired fraction of the volume of the attic space to be ventilated. When the bags are inflated from the evacuated condition to the inflated condition, they displace a volume of atmosphere equal to the difference between the cumulative volume of the bags in the evacuated condition and the cumulative volume of the bags in the inflated condition. The bags are then evacuated from the inflated condition to the fully evacuated condition or at least a substantially evacuated condition so as to draw ventilation air into the attic space through one or more ventilation inlets to the attic space.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to ventilation systems for enclosed spaces, and more particularly, to ventilation systems employing inflatable elements to displace the atmosphere from an enclosed space.

BACKGROUND OF THE INVENTION

The attic space included in many houses and other buildings can have a significant impact on cooling requirements for the inhabited portions of the building. In hot, sunny weather, sunlight incident on the roofing material quickly heats the material and much of this heat is eventually transferred to the attic air. The heat accumulated in an attic space may be transferred to the inhabited areas of the building by conduction through ceiling materials even when the ceiling is well insulated. Hot air trapped in an attic space can also leak into inhabited areas through utility and other openings in ceilings and walls.

Numerous different systems have been developed to ventilate the hot air from an attic and replace it with cooler air from outside. Attic ventilation systems may generally be categorized as passive systems or forced-air systems. Passive attic ventilation systems typically include exhaust vents located at the high points of the roof structure and inlet openings located at lower points of the roof system, commonly along the soffits of the roof structure. This type of passive ventilation system allows hot attic air to rise out through the roof vents while cooler air is drawn in through the lower inlets. However, while hot air does rise in the attic space and eventually flow out through the roof vents to be replaced by cooler air entering through the lower inlets, these types of passive attic ventilation systems generally provide insufficient circulation through the attic to prevent heat from building up in the attic space.

Forced-air type attic ventilation systems use wind-driven or motor-driven fans to move air to and/or from an attic. While such devices can move air much more quickly than passive attic ventilation systems, they are typically more expensive. Furthermore, although fans may be capable of displacing a large amount of air, they may move the air in such a way as to create narrow flow channels through the attic space. If such channels occur, a portion of the air in the attic may remain stagnant, and the attic will not be effectively ventilated. Such incomplete ventilation may cause hot air to remain in the attic and cause undesirable heating in the inhabited areas of the building.

SUMMARY OF THE INVENTION

The present invention includes methods and apparatus employing positive displacement for ventilating an enclosed space, particularly an attic space. The positive displacement ensures that atmosphere is effectively removed from the space to be ventilated.

One preferred method according to the present invention uses inflatable bags to ventilate an attic space. The method includes inflating one or more inflatable bags in the attic space from a first evacuated condition to an inflated condition. The inflatable bags are configured such that when they are in an evacuated condition, they take up a relatively small space in the attic space to be ventilated. In the inflated condition, however, the bags have a cumulative volume much larger than the cumulative volume of the bags when in the evacuated condition, and make up a desired fraction of the volume of the attic space to be ventilated. When the bags are inflated from the evacuated condition to the inflated condition, they displace a volume of atmosphere equal to the difference between the cumulative volume of the bags in the evacuated condition and the cumulative volume of the bags in the inflated condition. This volume of displaced atmosphere makes up desired fraction of the atmosphere within the attic, and is displaced through one or more ventilation outlets associated with the attic space as the bags are inflated. The bags are then evacuated from the inflated condition to the fully evacuated condition or at least a substantially evacuated condition (that is, a second evacuated condition) so as to draw ventilation air into the attic space through one or more ventilation inlets to the attic space.

The “desired fraction” of attic atmosphere which is displaced as the bags are inflated may be any significant fraction. Preferably, the desired fraction of atmosphere which is displaced as the bags are inflated is approximately thirty percent (30%) or more of the total volume of the attic space to be ventilated. However, lesser fractions of the total attic space volume, even as little as about ten percent (10%) can be used to effectively ventilate an attic space.

Although methods according to the present invention have particular application to ventilating attic spaces in homes and other buildings, the methods may also be employed in ventilating other enclosed spaces. Regardless of the particular enclosed space to which a method according to the invention is applied, the invention is well suited for displacing atmosphere having a first physical characteristic such as temperature, humidity, contaminant level, or some combination of these, and for drawing in atmosphere having a second physical characteristic. In one example, inflating the bag or bags in the enclosed space may displace and expel a desired fraction of atmosphere in the enclosed space at a first temperature. Evacuating the bag or bags to the evacuated condition may be applied so as to draw in atmosphere at a temperature that is significantly below or above the first temperature.

An apparatus according to the present invention includes one or more inflatable bags, each inflatable bag having a control opening. The one or more inflatable bags are sized so that when they are in an inflated condition they occupy a cumulative volume representing a desired fraction of a space to be ventilated. A blower is included in the apparatus along with a manifold which preferably includes an arrangement of conduits and a flow switching arrangement. The manifold operates to selectively connect the blower to the respective control opening of each bag to enable the blower to impress a desired air flow through each control opening. In particular, when the flow switching arrangement of the manifold is placed in a first condition it connects the blower to each control opening so as to enable the blower to impress a flow of air into each control opening to inflate each bag and thereby displace atmosphere from the space to be ventilated. When the flow switching arrangement is in a second condition, it connects the blower to each control opening so as to enable the blower to impress an opposite flow through the control opening of each bag to evacuate the bags. This flow out of the bags causes the bags to deflate and take up less volume in the space to be ventilated. A replacement atmosphere is drawn in to the space to be ventilated as the bags deflate.

These and other advantages and features of the invention will be apparent from the following description of the preferred embodiments, considered along with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of an apparatus according to the present invention, with the inflatable bags in an evacuated condition in a space to be ventilated.

FIG. 2 is a diagrammatic representation of the same apparatus shown in FIG. 1, but with the inflatable bags in an inflated condition.

FIG. 3 is a side view of an inflatable bag according to a first embodiment of the invention, with the bag shown in an evacuated condition.

FIG. 4 is a side view of the inflatable bag shown in FIG. 3, but with the bag in an inflated condition.

FIG. 5 is a side view of an inflatable bag according to a second embodiment of the present invention, with the bag shown in an evacuated condition.

FIG. 6 is a side view of the inflatable bag shown in FIG. 5, but with the bag in an inflated condition.

FIG. 7 is a side view of an inflatable bag according to a third embodiment of the invention, with the bag shown in an evacuated condition.

FIG. 8 is a side view of the inflatable bag shown in FIG. 7, but with the bag in an inflated condition.

FIG. 9 is a front view of the evacuated inflatable bag shown in FIG. 7.

FIG. 10 is a view inside an attic space showing a first implementation of inflatable bags within the attic space.

FIG. 11 is a view inside an attic space showing a second implementation of an inflatable bag within the attic space.

FIG. 12 is a diagrammatic representation of a blower and flow switching arrangement according to one form of the invention.

FIG. 13 is a diagrammatic representation similar to FIG. 12, but with the blower connected in a reversed flow position.

FIG. 14 is a diagrammatic representation of a blower and an alternate flow switching arrangement.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following description, the diagrammatic representations shown in FIGS. 1 and 2 will be referenced to provide an overall description of the features and operation of an apparatus embodying the principles of the present invention. FIGS. 4-9 will be referenced to describe examples of inflatable bags and bag attachment configurations that may be employed according to the present invention. FIGS. 10 and 11 will be referenced to describe how multiple inflatable bags may be arranged in implementations of the present invention. FIGS. 12 and 13 will be referenced to describe one preferred flow switching arrangement which may be used to fill and help evacuate an inflatable bag according to the invention, while FIG. 14 will be referenced to describe an alternate flow switching arrangement.

Referring to FIG. 1, a ventilation apparatus embodying the principles of the present invention includes inflatable bags 102, a blower 103, and a manifold made up of a flow switching arrangement 104 (abbreviated “FSA 104” in the figures) and system of bag connecting conduits 105. Each inflatable bag 102 is connected to the system of conduits 105 through a respective control opening 106. Inflatable bags 102 are located in an enclosed space 108 to be ventilated. An outlet opening 109 to enclosed space 108 allows atmosphere to flow out of the enclosed space, while an inlet opening 110 allows replacement atmosphere to enter the enclosed space.

A controller 112 is adapted to control the operation of both blower 103 and switching arrangement 104 to selectively inflate bags 102 from an evacuated condition to an inflated condition, and then evacuate the bags from the inflated condition to an evacuated condition. Controller 112 may operate using a number of different inputs shown diagrammatically in FIGS. 1 and 2 as a single line 114 to the controller. In the example system illustrated in FIGS. 1 and 2, controller 112 operates using an input from a temperature sensor 116 in enclosed space 108, a temperature sensor 117 providing a temperature for ambient air outside of the enclosed space, and a pressure sensor 118 adapted to provide a signal representing the pressure within inflatable bags 102. Pressure sensor 118 is preferably located to sense the pressure within a suitable one of the bag connecting conduits 105.

FIG. 1 shows inflatable bags 102 diagrammatically in an evacuated condition in which they each take up relatively little of the volume defined by enclosed space 108. This evacuated condition of the inflatable bags 102 represents a starting condition for a cycle of operation of the present invention. Beginning at the evacuated condition of bags 102 shown in FIG. 1, controller 112 operates to activate blower 103 and place flow switching arrangement 104 in condition (a first condition) to allow the blower to direct air through conduits 105 and into the control opening 106 of each inflatable bag 102. This air flow impressed through control openings 106 inflates each bag 102 from the evacuated condition shown in FIG. 1 and in dashed lines in FIG. 2, to an inflated condition shown by the solid lines for bags 102 in FIG. 2. The dashed lines in FIG. 2 are provided to better show the difference in volume taken up by each bag 102 in the inflated condition as opposed to the evacuated condition. In preferred implementations of the invention, each bag 102 in the inflated condition takes up many times the volume of the same bag in the evacuated condition. In any event, as inflatable bags 102 are inflated to the condition shown by the solid lines in FIG. 2, the bags displace atmosphere within enclosed space 108 and force the atmosphere out through ventilation outlet opening 109. The size and inflation of bags 102 are controlled according to the invention so that the cumulative volume of the bags in the inflated condition shown by the solid lines for the bags in FIG. 2 makes up a desired fraction of the volume of the space 108 to be ventilated. The cumulative volume of the bags 102 in the inflated condition as compared to the bags in the evacuated condition and to the overall volume of space 108 causes a desired fraction of the atmosphere in space 108 to be displaced out ventilation outlet opening 109 as the bags 102 go from the evacuated condition shown in dashed lines in FIG. 2 to the inflated condition shown in the solid lines. A desired fraction of the atmosphere displaced from space 108 may be as little as ten percent (10%). However, the more preferred implementations will displace between twenty to thirty percent (20-30%) or more of the overall volume of space 108.

Once inflatable bags 102 reach the desired inflated condition shown by the solid lines for the bags in FIG. 2, controller 112 causes flow switching arrangement 104 to switch to an evacuation part of the cycle of operation. In this part of the cycle of operation, a vacuum side (that is, an intake side) of blower 103 is preferably connected via flow switching arrangement 104 to conduits 105 to impress a flow of air out of each bag 102 through the respective bag control opening 106. It will be appreciated that as inflatable bags 102 deflate to an evacuated condition taking up far less volume in space 108, atmosphere from outside space 108 must be drawn in to replace the atmosphere that was displaced on the inflation part of the cycle of operation. In the illustrated example, the separate ventilation inlet 110 allows outside atmosphere to flow into space 108 as bags 102 deflate to an evacuated condition.

The cycle of operation described above, that is, the inflation of the bags 102 to the inflated condition and then evacuation to an evacuated condition, may be performed multiple times in close succession in order to ventilate space 108. On each cycle of operation, the system displaces the desired fraction of the atmosphere in space 108 and draws in a substantially equal volume of replacement atmosphere. This positive displacement of atmosphere and replacement provides a very effective level of ventilation for space 108 and avoids many of the problems associated with prior ventilation systems for enclosed spaces such as an attic space. Whether one cycle of operation is performed or multiple cycles of operation, it should be appreciated that the evacuated condition of the bags at the start of the cycle and at the end of the cycle may be somewhat different since it may be impractical to completely evacuate the bags in a given implementation. Thus, the evacuated condition of the bags may be referred to herein and in the following claims as different evacuated conditions, for example, a first and second evacuated condition. This usage merely indicates that the level of evacuation for the bags is somewhat variable and that it is not necessary to fully evacuate each bag on each cycle of operation. It is sufficient that the difference between the inflated condition of the bags and the evacuated condition (both at the start and end of the operation cycle) is such that the desired fraction of atmosphere is displaced from the space to be ventilated and a desired fraction of replacement atmosphere is drawn in to the space to be ventilated on each cycle of operation.

One preferred application of the invention is to ventilate an attic space in warm weather where the attic air can climb to temperatures far exceeding the ambient temperature. Temperature sensors such as sensor 116 inside the space to be ventilated and ambient air sensor 117 may be used together with controller 112 to ensure that the system performs a cycle of operation only when a certain differential exists between the air temperature in the space to be ventilated and the outside or ambient air that will be used as replacement air in the operation cycle. Controller 112 is preferably set so that the air temperature in the space to be ventilated is at least ten (10) degrees Fahrenheit higher than the ambient air before the system performs a cycle of operation. Although a 10° F. differential is preferred to trigger a cycle of operation for attic space ventilation purposes, other differentials may be employed within the scope of the invention, in particular a temperature differential between approximately 5° F. and 20° F. A temperature differential between the air temperature in the space to be ventilated and the ambient air temperature may also be used to stop the operation of the ventilation system. For example, where the start operation temperature differential is 10° F., controller 112 may be programmed to discontinue operation once the sensors 116 and 118 show a temperature differential of approximately five (5) degrees Fahrenheit of enclosed air temperature to ambient air temperature. Regardless of the temperature differential or other input or set of inputs used to discontinue operation of system 100, controller 112 is preferably programmed to complete a cycle and return the bags to an evacuated condition, and then discontinue operation at that point.

Each cycle of operation of apparatus 100 is preferably controlled using the pressure signal provided by pressure sensor 118. In particular, controller 112 may be programmed so that it operates flow switching arrangement 104 and blower 103 to inflate bags 102 until some predetermined pressure is reached in the bags, as indicated by the pressure sensed in conduit 105. That pressure may be set as a pressure at which bags 102 are inflated and expanded to a certain degree corresponding to the desired level of displacement of atmosphere from enclosed space 108. Alternately to a pressure signal, controller 112 may rely on a signal from a switch which is physically actuated by contact with a given bag 102 when the bag is inflated to a desired degree. Numerous other inputs such as tension in the material of bags 102, or length or width of the bags (as indicated by optical sensors for example), may be used to provide an indication when the bags are inflated to the desired degree, and thereby allow controller 112 to switch the operation of flow switching arrangement 104 to evacuate bags 102 and complete a cycle of operation. It should also be appreciated that additional control elements may be used in the operation to inflate and evacuate bags 102. For example, a pressure relief valve 119 may be included in conduit 105 or elsewhere in the system to ensure that some maximum pressure is not exceeded in bags 102.

Although the application to ventilate a space in order to reduce the temperature in the space represents a preferred application of the present invention, numerous other applications are possible within the scope of the invention as defined in the claims below. For example, apparatus 100 may be adapted to provide a replacement atmosphere that is warmer than the atmosphere displaced from space 108. In another example, the replacement atmosphere may be less humid or conceivable more humid than the atmosphere displaced from the enclosed space. In yet another example, a positive displacement ventilation system according to the present invention may be employed to decrease the concentration of a toxic or other gas within the enclosed space. Of course in applications that do not necessarily alter temperature in the enclosed space 108, controller 112 may operate to control blower 103 and flow switching arrangement 104 using sensors suitable for sensing the desired atmospheric condition to be changed within the enclosed space.

It should also be noted that although a preferred application of the present ventilation system is in connection with controlling temperature in attic space, the present invention is also applicable for providing ventilation to control temperature in other types of enclosed spaces. For example, a positive displacement ventilation system within the scope of the present invention may be used to control temperatures in the passenger compartment of an automobile or truck. In this application, the inflatable bag or bags would be housed in the passenger compartment such that they may be expanded when the vehicle is not occupied and then evacuated so as to be housed in an unobtrusive fashion within seats, doors, and/or roof.

Controller 112 may comprise any suitable device for properly activating blower 103 and flow switching arrangement 104 in order to inflate and then evacuate bags 102 in an operation cycle as described above. For example, controller 112 may comprise a programmable logic controller which has the capacity to receive the necessary control inputs, such as the inputs from sensors 116, 117, and 118 in FIGS. 1 and 2, and provide the desired control outputs to blower 103 and flow switching arrangement 104 in response to those inputs. Controller 112 may alternatively comprise a programmable logic relay device which includes control relays for selectively energizing a circuit for blower 103, and one or more actuators which may be included in flow switching arrangement 104.

Depending upon the purpose of the ventilation provided according to the invention, it may be important to control the location from which the replacement atmosphere is taken, or the location at which the displaced atmosphere is expelled from the space to be ventilated (such as space 108 in FIGS. 1 and 2). For example, where system 100 is intended to ventilate and cool a house attic space, the replacement air drawn in through ventilation inlet 110 should be air that is as cool as possible. A preferred implementation in this case employs multiple ventilation inlets 110 located under the roof eaves (that is, in the soffit) at different points around the periphery of the roof. This preferred implementation may also use multiple ventilation outlets preferably located along the ridge or ridges of the roof. To ensure that displaced air is expelled only through the ridge-mounted ventilation outlets 109 and air is drawn in only through the soffit-mounted ventilation inlets 110, each such outlet and each such inlet is configured to allow only one-way flow there through. For example, each ventilation outlet may have an associated flap 120 which unseats to allow flow out through the outlet, but seats to prevent flow into the attic through the outlet. Similarly, each ventilation inlet 110 may include a flap 121 or other member which unseats to allow flow into the attic, but seats to prevent flow out of the attic through the inlet.

In other attic ventilation implementations, replacement air may be taken from a location adjacent the building which is shaded and protected at least somewhat from heating by solar radiation. For example, one or more ventilation inlets may include a suitably sized duct which extends to an area from which replacement air is to be taken. In this alternate implementation, one-way ridge vents may be used as ventilation outlets. Alternatively, one or more ventilation outlets may include a duct for directing the hot air displaced from the attic space to some desired location, preferably far removed from the area from which the replacement air is drawn.

One preferred implementation for ventilating a space to be cooled (such as an attic space) includes an arrangement for introducing a water mist into the stream of air directed from blower 103 to inflatable bags 102. This mist may provide some degree of evaporative cooling in the inflatable bags 102 to help remove heat from the space to be ventilated by heat transfer through the bag material. Since the added water is maintained in the bags 102 and conduits 105, it does not pose a risk of damage to the materials defining the space to be ventilated. A preferred device 124 for introducing a water mist is located in the conduits 105 adjacent to flow switching arrangement 104. Although the details of misting device 124 are not shown in FIGS. 1 and 2, the device may include a water supply and a misting nozzle extending from the water supply into the conduit 105. Misting device 124 is preferably controlled through controller 112 so as to inject mist only when bags are being inflated, and perhaps only during periods of relatively low ambient humidity.

FIGS. 3 and 4 show further details of an inflatable bag 302 that may be used according to the present invention. It will be appreciated that bag 302 corresponds to the diagrammatically represented bags 102 shown in FIGS. 1 and 2. Inflatable bag 302 is illustrated in FIGS. 3 and 4 suspended in an attic space 303 to be ventilated. In particular, bag 302 is suspended from a hook 304 fixed to a ridge beam 306 in the attic space 303 between two adjacent rafters 307. In order to facilitate the suspension from hook 304, bag 302 includes a ring 308 which may be slipped over the end of the hook. The control opening of bag 302 in the implementation of FIGS. 3 and 4 is located at the bottom of the bag in the orientation of the drawings, and is defined through a suitable connector 310 which is adapted to connect to flexible hose 311. Flexible hose 311 is connected to a distribution conduit 312 and together these elements correspond to the conduits 105 shown in FIGS. 1 and 2. FIGS. 3 and 4 also show that bag 302 includes a weighting element 314 connected at the lower end of the bag in the orientation of the drawings. Bag 302 is made of a suitable flexible and air-tight material, with a series of longitudinal pleats 315.

In a cycle of operation of a system according to the invention employing bag 302, the bag is initially in the evacuated condition shown in FIG. 3. In this position, the weight of the bag material together with the weight of connector 310, flexible hose 311, and weighting element 314 causes bag 302 to elongate, with the bag pleats 315 folding so that the bag takes up relatively little volume of attic space 303. However, as bag 302 is filled, preferably with air supplied from a blower such as blower 103 shown in FIGS. 1 and 2, the bag expands to a position illustrated in FIG. 4. Pleats 315 unfold at least partially to facilitate the expansion of bag 302. As the sides of bag 302 bow outwardly during inflation, the lower end of the bag, and particularly connector 310 and weighting element 314 are lifted, together with at least a portion of flexible hose 311, from the position shown in FIG. 3. Once bag 302 is inflated to the desired degree to displace atmosphere from attic space 303, the bag is then evacuated to return it to a suitable evacuated condition to draw replacement atmosphere into the attic space. This evacuation is preferably accomplished in part by applying the vacuum or intake of a blower such as that shown at 103 in FIGS. 1 and 2, to help withdraw air from the bag. Also, weighting element 314, together with the weight of the bag material, connector 310, and at least a portion of hose 311 exert a downward force on the lower end of bag 302 to help force air out of the bag and return the bag to the elongated and evacuated condition shown in FIG. 3.

Although FIGS. 3 and 4 show only a single bag 302, it will be appreciated that numerous separate inflatable bags may be needed in attic space to displace the desired fraction of attic atmosphere according to the present invention. Inflatable bags such as bag 302 may be spaced apart along the length of the ridge beam and positioned between adjacent rafters of the building structure. Also, as discussed below in connection with FIG. 10, multiple bags such as bag 302 may be spaced apart in a direction transverse to the longitudinal axis of ridge beam 306.

It should be appreciated that numerous variations on the arrangement shown in FIGS. 3 and 4 may be employed within the scope of the present invention. For example, although bag 302 is shown as being suspended vertically in attic space 303, a bag may alternately be suspended at both ends along the slope of the attic space in a direction transverse to the view shown in FIGS. 3 and 4. In this orientation, the bag in the evacuated condition would not hang straight down, but would form a bowed shape between the supported ends. In this configuration the weight of the connector to the bag and weight of the flexible hose would not help evacuate the bag when evacuation is desired. Rather a weighting element corresponding to weighting element 314 in FIGS. 3 and 4 could be connected to the bag at some intermediate point to exert a downward force which would assist in forcing air out of the bag during the evacuation portion of the operation cycle.

FIGS. 5 and 6 show an alternate embodiment including an inflatable bag 502 corresponding to inflatable bag 102 in the system 100 shown in FIGS. 1 and 2. In this embodiment, bag 502 is suspended from a conduit 512 located in an upper part of an attic space 503 below ridge beam 506. Similarly to bag 302 shown in FIGS. 3 and 4, bag 502 includes longitudinal pleats 515 and a connector 510 for connecting to a corresponding fitting associated with conduit 512. Bag 502 is suspended between adjacent rafters 507 of the building structure. Unlike bag 302 shown in FIGS. 3 and 4, bag 502 includes a weighting element 514 at the end opposite to connector 510. The operation of a system employing bag 502 is similar to that described above in connection with FIGS. 3 and 4. However, in the case of bag 502, it is only the weighting element 514 and the weight of the bag material itself which exerts the downward force to help evacuate air from the bag and return the bag from the inflated condition shown in FIG. 6 to the evacuated condition shown in FIG. 5. As with bag 302 shown in FIGS. 3 and 4, bag 502 need not be suspended vertically in the illustrated position, but may be suspended at both ends to follow the slope of the roof in a direction transverse to ridge beam 506. In this configuration, a weighting element corresponding to weighting element 514 would preferably be positioned at some intermediate position along the length of the bag material in position to exert a downward force to help evacuate the bag 502 in the desired portion of the system operation cycle.

FIGS. 7-9 show another type of inflatable bag 702 corresponding to the bag 102 in FIGS. 1 and 2. As can be appreciated best from the side view of FIG. 9, bag 702 has a rectangular shape when in an evacuated condition. This is in contrast to bags 302 and 502 which are substantially symmetrical about their respective longitudinal axis. Bag 702 has end pleats 715 that allow the sides 716 to separate as the bag is inflated to the condition shown in FIG. 8, without significantly changing the dimension along axis L in FIG. 9. This configuration for bag 702 has the advantage that the bag may be made as long as necessary in the direction of axis L in order to extend further across the width of a space to be ventilated. This advantage will be described further below in connection with FIG. 11. Bag 702 includes multiple top connecting points 708 (shown in FIG. 9) from which the bag may be suspended in a space 703 to be ventilated. Similarly to the bag 302 shown in FIGS. 3 and 4, bag 702 includes a connector 710 at its lower end for connecting to a flexible hose 711 which is in turn connected to a conduit 712. Bag 702 also includes a weighting element 714 which serves the same function as weighting element 314 discussed above in connection with FIGS. 3 and 4. Although FIGS. 7-9 do not show bag 702 positioned in any particular sort of space to be ventilated, it will be appreciated that the configuration of bag 702 is well suited to use in an attic space, hung between adjacent rafters of the building roof structure, and with the axis L shown in FIG. 9 extending perpendicular to the roof structure ridge beam and in a plane parallel to the planes of the adjacent rafters.

FIG. 10 shows one preferred arrangement of inflatable bags 1002 in an attic space 1003 according to the present invention. Bags 1002 are each similar to bag 302 shown in FIGS. 3 and 4, but are each suspended in a different position along between adjacent rafters 1007 and truss members 1009. In particular, FIG. 10 illustrates that multiple bags 1002 may be positioned across the width of an attic space, transverse to ridge beam 1006. In order to facilitate the positioning between adjacent rafters 1007, each bag 1002 may be suspended from a cable or other member 1004 which itself is supported between adjacent rafters 1007 so as to extend perpendicular to the plane of the drawing in FIG. 10.

In order to perform the inflation and evacuation of each bag 1002 (as described above in connection with corresponding bags 102 shown in FIGS. 1 and 2) the implementation shown in FIG. 10 includes a conduit 1012 extending transverse to ridge beam 1006. Each bag 1002 is connected to conduit 1012 through a respective flexible hose 1011. In order to provide greater displacement of atmosphere from attic space 1003, one or more additional sets of bags 1002 may be positioned between different adjacent rafters 1007 along the length of ridge beam 1006. Each set of bags 1002 may be configured similarly to that shown in FIG. 10, with each bag having a respective flexible hose connecting the bag to a transverse conduit similar to conduit 1012. Each such transverse conduit may be connected to a longitudinal conduit 1013 which extends perpendicular to the plane of FIG. 10. The conduits 1012 and 1013, and flexible hoses 1011 all correspond to the conduit arrangement 105 in the diagrammatic representation of FIGS. 1 and 2. Each bag 1002 is also associated with a weighting element 1014 which performs the same function as weighting element 314 shown in FIGS. 3 and 4.

It should be noted that although bags 1002 are shown in FIG. 10 as being connected to conduits from below, as in the arrangement shown in FIGS. 3 and 4, alternative implementations may use conduits positioned above the bags in the configuration shown in FIGS. 5 and 6. Whether connected to conduits from above or below, bags 1002 may be spaced apart in the direction perpendicular to the plane of FIG. 10 in a suitable arrangement. Bags 1001 need not be provided between each adjacent pair of rafters 1007 in order to provide effective ventilation according to the present invention. Also, it will be appreciated that bags 1002 may be staggered along the axis perpendicular to the plane of FIG. 10, and need not line up in that direction. It should also be appreciated that the four bags 1002 are shown in FIG. 10 only as an example, and that more or fewer bags may be used in the direction transverse to ridge beam 1006. In any event, bags 1002 closer to the apex of the roof structure may be somewhat longer than the bags further away from the apex of the roof structure. This tailoring of the bag length to its position in the space to be ventilated helps maximize the displacement of atmosphere according to the present invention.

FIG. 11 shows an implementation in which a single bag 1102, which may be similar to bag 702 shown in FIGS. 7-9, extends across the width of a space to be ventilated 1103. In this example, the space to be ventilated 1103 is again an attic space which includes a ridge beam 1106, rafters 1107, and supporting trusses 1109. Bag 1102 is suspended from multiple points so as to hang between adjacent rafters 1107 and the truss members 1109 which help support the rafters. In this embodiment, bag 1102 includes multiple connectors 1110 which provide connection points for multiple flexible hoses 1111. Each connector 1110 is associated with a respective weighting element 1114 which provides the same function as weighting element 314 described above in connection with FIGS. 3 and 4. As in the embodiment shown in FIG. 10, the various flexible hoses 1111 are connected to a laterally extending conduit 1112, and the laterally extending conduit is connected to a conduit 1113 which extends generally perpendicular to ridge beam 1106. The implementation using single wide bags 1102 also preferably includes multiple bags of the same type or perhaps different types spaced apart along the length of the space to be ventilated to provide increased displacement volume according to the invention.

Although the implementations shown in FIGS. 10 and 11 are intended to show representative examples of the manner in which the present positive displacement ventilation system may be implemented, it should be appreciated that numerous variations on these examples are possible within the scope of the present invention and the claims set out below. For example, bags such as shown at 1002 in FIG. 10, or bags such as shown at 1102 in FIG. 11 may be spaced apart in any suitable fashion in the space to be ventilated. Where laterally elongated bags are employed such as bag 1102 in FIG. 11 and bag 702 in FIGS. 7-9, the bags may be sized to extend along just a portion of the length or width of the space to be ventilated so that a single bag does not extend across the entire length or width. In any event, inflatable bags need not be placed between each adjacent set of rafters in an attic space application. Also, any suitable arrangement of conduits may be used to direct air to the bag(s) during the inflation part of the operation cycle, and withdraw air from the bag(s) during the evacuation part of the operation cycle. Although the above examples show a single set of conduits for both filling and evacuating the bag(s), a set of conduits may be used for filling the bag(s) and a separate set of conduits may be used for evacuating the bags(s). Furthermore, the specific numbers of inflatable bags shown in the figures are shown only for purposes of example and are not intended to be limiting. A given application of the present invention may include one inflatable bag or numerous bags to provide the desired degree of atmosphere displacement.

FIGS. 12 and 13 provide a diagrammatic representation of one preferred flow switching arrangement 1201, which cooperates with a blower 1202 to inflate and then evacuate one or more inflatable bags (corresponding to bags 102 in FIGS. 1 and 2, but not shown in FIGS. 12 and 13). Switching arrangement 1201 corresponds to switching arrangement 104 shown in FIGS. 1 and 2, and blower 1202 corresponds to blower 103 shown in those earlier figures. As shown in FIGS. 12 and 13, flow switching arrangement 1201 a first valve plate 1204 and a second valve plate 1206. First valve plate 1204 includes two openings, an outlet opening 1207 connected to an output of blower 1202 through output conduit 1208, and a return opening 1210 connected to a vacuum inlet of blower 1202 through inlet line 1211. Second valve plate 1206 includes three openings, an active opening 1214 connected to a conduit 1215 leading to the control openings of the bag or bags in the given system, a release opening 1217, and a supply opening 1218.

First valve plate 1204 and second valve plate 1206 are adapted to move relative to each other so that the two plates may be aligned in a first condition or a second condition. FIG. 12 illustrates the first condition in which active opening 1214 of second valve plate 1206 aligns with outlet opening 1207 of first valve plate 1204, and supply opening 1218 of the second valve plate aligns with return opening 1210 of the first valve plate. When blower 1202 is operated with valve plates 1204 and 1206 in this alignment, the output of the blower is applied to conduit 1215 to fill the bag or bags connected to the conduit. This operation corresponds to the fill portion of the operation cycle described above in connection with FIGS. 1 and 2.

FIG. 13 illustrates the second condition for the first and second valve plates 1204 and 1206, in which active opening 1214 and conduit 1215 align with return opening 1210 and outlet opening 1207 aligns with release opening 1217. When blower 1202 operates with valve plates 1204 and 1206 in this second condition, the blower actively draws air through conduit 1215 from the bag or bags connected to that conduit, and exhausts the air to the atmosphere through the blower outlet conduit 1208 and the aligned outlet opening 1207 and release opening 1217. This operation corresponds to the evacuation portion of the operation cycle discussed above in connection with FIGS. 1 and 2.

In a preferred implementation of the flow switching arrangement 1201 shown in FIGS. 12 and 13, second valve plate 1206 is adapted to be moved relative to first valve plate 1204 to provide the relative movement apparent from the figures. To accommodate this movement of second valve plate 1206, conduit 1215 is either a flexible conduit or is otherwise configured so that the end connected to the second valve plate may move as the plate moves. The required movement between plates 1204 and 1206 may be produced in any suitable manner. A preferred implementation may employ a suitable linear actuator (not shown) which is connected to second valve plate 1206 and is operable under a control signal to shift the position of the second valve plate as required to fill and evacuate the inflatable bag or bags as described in connection with FIGS. 1 and 2. The control signal for the actuator may be provided by the controller 112 shown in FIGS. 1 and 2.

It will also be appreciated that seals are required between first valve plate 1204 and second valve plate 1206 to facilitate efficient flow along the desired flow paths defined by the two valve plates. A close tolerance between the abutting surfaces of the two plates 1204 and 1206 may provide suitable seals in some cases. Otherwise, a gasket or O-ring arrangement may be used between the two plates 1204 and 1206 to provide the desired seals, but allow the required relative movement between the two plates. It should also be appreciated that the size of the various plate openings 1207, 1210, 1214, 1217, and 1218 will depend on the flow rate required to fill and evacuate the inflatable bags according to the method described in connection with FIGS. 1 and 2. In a typical implementation for an attic space ventilation application, each of these valve plate openings may be approximately three to six inches in diameter.

FIG. 14 shows an alternate flow switching arrangement 1401 connected to a blower 1402. These elements correspond to the flow switching arrangement 104 and blower 103, respectively, shown in FIGS. 1 and 2. Flow switching arrangement 1401 includes a fill valve 1404 connected to an outlet of blower 1402 via a blower output conduit 1405 and also connected to a conduit 1407 which corresponds to the conduit 105 shown in FIGS. 1 and 2 or system of conduits connected to the bags 102 shown in those figures. Flow switching arrangement 1401 also includes an evacuation valve 1408 connected between conduit 1407 and a blower intake conduit 1410 which is connected to the intake of blower 1402. In addition to valves 1404 and 1408, flow switching arrangement 1401 also includes an intake valve 1412 and release valve 1413. Intake valve 1412 is connected between the atmosphere and blower intake conduit 1410, while release valve is connected between the atmosphere and blower output conduit 1405.

Flow switching arrangement 1401 is adapted to be alternatively placed in a first condition in which the blower 1402 inflates the bag or bags connected to conduit 1407, or a second condition in which the blower helps evacuate the bags or bags (the bags not being shown in FIG. 14). In the first condition, fill valve 1404 and intake valve 1412 are open, and evacuation valve 1408 and release valve 1413 are closed. In this condition, blower 1402 may be activated to receive air from the atmosphere through intake valve 1412 and intake conduit 1410, and blow this air through fill valve 1404 and conduit 1407 to inflate the bag or bags connected to output conduit. Operation in this first condition corresponds to the fill or inflation portion of the cycle of operation described above in connection with FIGS. 1 and 2. In the second condition of flow switching arrangement 1401, the position of the valves 1404, 1408, 1412, and 1413 is reversed as compared to the positions for the fill portion of the operation cycle. That is, in the second condition of flow switching arrangement 1401, output valve 1404 and intake valve 1412 are closed, while evacuation valve 1408 and release valve 1413 are open. When blower 1402 is operated while the valves are in these positions, the blower draws air through conduit 1407 (and from the bag or bags connected to that conduit) through evacuation valve 1408 and intake conduit 1410. Blower 1402 also exhausts air to the atmosphere through blower output conduit 1405 and release valve 1413. This operation corresponds to the evacuation portion of the operation cycle described above in connection with FIGS. 1 and 2 to evacuate the bags 102 shown in those figures.

Each of the valves 1404, 1408, 1412, and 1413 is illustrated schematically in FIG. 14 as being a remote control valve which includes a respective actuator (a solenoid for example) for switching the valve position in response to a suitable control signal. Control signals for operating the valves 1404, 1408, 1412, and 1413, as well as a control signal for operating blower 1402 may be generated by a suitable controller such as the controller 112 described above in connection with FIGS. 1 and 2.

As used herein, whether in the above description or the following claims, the terms “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” and the like are to be understood to be open-ended, that is, to mean including but not limited to. Any use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another, or the temporal order in which acts of a method are performed. Rather, unless specifically stated otherwise, such ordinal terms are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term).

The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit the scope of the invention. Various other embodiments and modifications to these preferred embodiments may be made by those skilled in the art without departing from the scope of the present invention. 

1. A method for ventilating an attic space, the method including: (a) inflating one or more inflatable bags from a first evacuated condition in the attic space to an inflated condition in the attic space, the one or more inflatable bags having a total volume in the inflated condition which comprises a desired fraction of the volume of the attic space so that the inflation of the one or more inflatable bags from the first evacuated condition to the inflated condition displaces a desired fraction of the atmosphere in the attic space through one or more ventilation outlets from the attic space; and (b) evacuating the one or more inflatable bags in the attic space from the inflated condition to a second evacuated condition, the evacuation of the one or more inflatable bags drawing ventilation air into the attic space through one or more ventilation inlets to the attic space.
 2. The method of claim 1 wherein evacuating the one or more inflatable bags includes applying a reduced pressure to the interior of each respective inflatable bag.
 3. The method of claim 2 wherein evacuating the one or more inflatable bags includes applying an elongation force to each respective inflatable bag to elongate each respective bag along a first axis thereof and reduce a dimension of the respective bag along a second axis transverse to the first axis, the elongation force being a force exceeding a force resulting from the mass of the respective inflatable bag.
 4. The method of claim 1 wherein evacuating the one or more inflatable bags includes applying an elongation force to each respective inflatable bag to elongate each respective bag along a first axis thereof and reduce a dimension of the respective bag along a second axis transverse to the first axis, the elongation force being a force exceeding a force resulting from the mass of the respective inflatable bag.
 5. The method of claim 1 wherein the one or more inflatable bags are suspended within the attic space and wherein inflating the one or more inflatable bags includes raising a lower surface of each inflatable bag upwardly in the attic space.
 6. The method of claim 1 wherein inflating the one or more inflatable bags and evacuating the one or more inflatable bags includes operating a blower which is connected to each of the one or more inflatable bags through a manifold.
 7. The method of claim 1 wherein inflating the one or more inflatable bags includes applying positive pressure from a blower to the one or more inflatable bags through a valve structure in a first position, and wherein evacuating the one or more inflatable bags includes applying a vacuum from the blower to the one or more inflatable bags through the valve structure in a second position.
 8. A method for modifying the atmospheric temperature in an enclosed space, the method including: (a) inflating an inflatable bag from a first evacuated condition in the enclosed space to an inflated condition in the enclosed space to displace a desired fraction of an atmosphere from the enclose space, the displacement causing a portion of the atmosphere from the enclosed space to be expelled from the enclosed space through one or more outlet openings to the enclosed space, wherein the expelled atmosphere has a first physical characteristic; and (b) evacuating the inflatable bag in the enclosed space to evacuate the inflatable bag from the inflated condition to a second evacuated condition, the evacuation of the inflatable bag drawing replacement atmosphere into the enclosed space through one or more ventilation openings to the enclosed space, wherein the replacement atmosphere has a second physical characteristic at the time it is drawn into the enclosed space, and wherein the second physical characteristic is different from the first physical characteristic.
 9. The method of claim 8 wherein the first physical characteristic comprises a first temperature and the second physical characteristic comprises a second temperature.
 10. The method of claim 9 wherein the second temperature is at least ten (10) degrees Fahrenheit below the first temperature.
 11. The method of claim 8 wherein the enclosed space is an attic space and wherein inflating the inflatable bag and evacuating the inflatable bag is performed with a single blower device.
 12. The method of claim 8 wherein the inflatable bag is suspended in the enclosed space and wherein inflating the inflatable bag includes raising a lower end of the inflatable bag to decrease the dimension of the inflatable bag along a first axis and increase the dimension of the inflatable bag along a second dimension extending transverse to the first dimension.
 13. The method of claim 12 wherein evacuating the inflatable bag includes applying an elongation force at the lower end of the inflatable bag, the elongation force being a force exceeding a force resulting from the mass of the inflatable bag.
 14. An apparatus including: (a) one or more inflatable bags, each inflatable bag having a control opening; (b) a blower; (c) a manifold adapted to selectively connect the blower to the respective control opening of each of the one or more inflatable bags to enable the blower to impress a desired air flow through each respective control opening; and (d) wherein the one or more inflatable bags are sized so that when they are in an inflated condition they occupy a total volume representing a desired fraction of a space to be ventilated.
 15. The apparatus of claim 14 wherein manifold includes: (a) a bag connecting conduit; and (b) a switching arrangement adapted to reside alternatively in a first condition and a second condition, the first condition connecting a fill outlet of the blower to the control opening of each of the one or more inflatable bags through the bag connecting conduit, and the second condition connecting a vacuum outlet of the blower to the inlet opening of each of the one or more inflatable bags through the bag connecting conduit.
 16. The apparatus of claim 15 further including a controller adapted to control the operation of the blower and control the condition of the switching arrangement in response to control inputs.
 17. The apparatus of claim 16 further including a pressure sensor connected to provide a pressure output indicating of the pressure in the one or more inflatable bags, and wherein the control inputs include the pressure output provided by the pressure sensor.
 18. The apparatus of claim 16 further including a first temperature sensor located to provide a temperature output indicating the temperature of an atmosphere in the space to be ventilated, and wherein the control inputs include the temperature output of the first temperature sensor.
 19. The apparatus of claim 18 further including a second temperature sensor located to provide a temperature output indicating the temperature of ambient atmosphere outside of the space to be ventilated, and wherein the control inputs include the temperature output of the second temperature sensor.
 20. The apparatus of claim 14 wherein at least one of the one or more inflatable bags is suspended in the space to be ventilated and further including a biasing weight connected to a lower end of the at least one inflatable bag to apply an elongating force to the at least one inflatable bag, the elongating force exceeding a force resulting from the mass of the at least one inflatable bag. 